Compressed image data generally is stored in a format that permits efficient access to each part of the compressed image data and the parameters for decompressing each part of the compressed image data. There are several standards that have been defined for bitstream formats for different kinds of compressed data. For example, there is a bitstream format defined by the MPEG-2 standard. Typically, such a bitstream format includes picture header information and picture information. The header information typically includes information about how to access the compressed image data and associated parameters for each block of an image. Such bitstream formats generally are designed to enable efficient access to the bitstream as a single serial stream of data. MPEG-2 defines “slices” of compressed data by placing “slice markers” in the data stream; however a slice can only be accessed by scanning the data stream for the slice markers.